Harness clamps for use when pipes are axially coupled are known in the art, but known clamps are not satisfactory in maintaining preload. The clamp halves and bolts may relax and initial preload is lost, resulting in leakage of fluids carried by the pipes.
Known prior art systems include that of Rung, et al. U.S Pat. No. 4,611,839, which describes a self-adjusting pipe clamp and coupling having buttresses including bolting pads. The ends of the coupling segments include inclined end faces for cooperation with the corresponding inclined end faces of an adjacent coupling segment to produce self-adjustment of the coupling and rigid clamping of the pipe ends upon tightening down of the coupling. The end portions of the clamp halves function as bolting pads. Springs for maintaining preload are not used.
Kennedy, Jr. et al., U.S. Pat. No. 4,026,586, describes a corrugated clamp for joining plain ends of pipe. An elastic gasket member serves as a liner between the clamp and pipes. Reenforcing plates are attached to ends of the corrugated clamping strip, and load deformation is absorbed by the corrugated strip.
The patent to Faint, U.S. Pat. No. 3,204,665, describes a pipe clamp including a gasket liner. Side casting lugs are described and bolts are each seated in a depression in a lug. The patent to Graham, et al., U.S. Pat. No. 3,089,212, describes another pipe clamp including a sealing gasket. An opposed lug structure is described to avoid bending of the bolts during tightening. Muto, U.S. Pat. No. 1,928,316, describes a pipe coupling having a bushing or packing of soft material.
Known prior patents do not address the problem of maintaining preload.